feat(arch): Add AArch64 / ARMv8i CPU support, cross-compilation & Linux Kconfig TUI

- Implement AArch64 HAL, vector table (16 aligned vectors), GICv2, Generic Timer, Stage-1 MMU (39-bit VA), PL011 UART
- Build unified multi-architecture abstraction layer in include/arch/arch.h
- Create interactive Linux-like Kconfig TUI menuconfig in scripts/kconfig/menuconfig.py
- Support make menuconfig, defconfig, x86_64_defconfig, aarch64_defconfig
- Update master Makefile for cross-compiling x86_64 (x86_64-elf-) and AArch64 (aarch64-linux-gnu-)
- Dynamic architecture awareness across printk, uname, neofetch, and LazyBox

include/arch/arch.h

@@ -0,0 +1,96 @@
+#ifndef _ARCH_ARCH_H
+#define _ARCH_ARCH_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#if defined(__x86_64__)
+#define ARCH_NAME "x86_64"
+#define ARCH_IS_64BIT 1
+#include <arch/x86_64/gdt.h>
+#include <arch/x86_64/idt.h>
+#include <arch/x86_64/isr.h>
+#include <arch/x86_64/pic.h>
+#include <arch/x86_64/pit.h>
+#include <arch/x86_64/cpuid.h>
+#include <arch/x86_64/paging.h>
+#include <arch/x86_64/io.h>
+
+static inline void arch_enable_interrupts(void) {
+    __asm__ volatile("sti");
+}
+
+static inline void arch_disable_interrupts(void) {
+    __asm__ volatile("cli");
+}
+
+static inline void arch_halt(void) {
+    __asm__ volatile("hlt");
+}
+
+static inline void arch_wait_for_interrupt(void) {
+    __asm__ volatile("sti; hlt");
+}
+
+static inline uint64_t arch_get_ticks(void) {
+    return pit_get_ticks();
+}
+
+static inline void arch_sleep(uint32_t ms) {
+    pit_sleep(ms);
+}
+
+#elif defined(__aarch64__) || defined(__arm64__)
+#define ARCH_NAME "aarch64"
+#define ARCH_IS_64BIT 1
+#include <arch/aarch64/arch.h>
+#include <arch/aarch64/cpu.h>
+#include <arch/aarch64/gic.h>
+#include <arch/aarch64/timer.h>
+#include <arch/aarch64/mmu.h>
+#include <arch/aarch64/uart.h>
+#include <arch/aarch64/io.h>
+
+static inline void arch_enable_interrupts(void) {
+    __asm__ volatile("msr daifclr, #2" ::: "memory");
+}
+
+static inline void arch_disable_interrupts(void) {
+    __asm__ volatile("msr daifset, #2" ::: "memory");
+}
+
+static inline void arch_halt(void) {
+    __asm__ volatile("wfi");
+}
+
+static inline void arch_wait_for_interrupt(void) {
+    __asm__ volatile("msr daifclr, #2; wfi" ::: "memory");
+}
+
+static inline uint64_t arch_get_ticks(void) {
+    return aarch64_timer_get_ticks();
+}
+
+static inline void arch_sleep(uint32_t ms) {
+    uint64_t count = (ms > 10) ? (ms / 10) : 1;
+    uint64_t target = aarch64_timer_get_ticks() + count;
+    while (aarch64_timer_get_ticks() < target) {
+        __asm__ volatile("wfi");
+    }
+}
+
+// Prototype declarations for timer/interrupt compatibility
+uint64_t pit_get_ticks(void);
+void     pit_sleep(uint32_t ms);
+
+#else
+#error "Unsupported Target CPU Architecture!"
+#endif
+
+// Generic Architecture API
+void        arch_early_init(void);
+void        arch_init(void);
+const char* arch_get_name(void);
+uint32_t    arch_get_cpu_id(void);
+
+#endif // _ARCH_ARCH_H